This invention further relates to a process for printing sheetlike or three-dimensionally configured substrates by the ink-jet process using these pigment preparations.
Inks for use in the ink-jet process have to meet a whole series of requirements: They have to have a viscosity and surface tension suitable for printing, they have to be stable in storage, ie. they should not coagulate and the dispersed, undissolved colorant should not settle out, they must not lead to blockage of the printer nozzle, which can likewise be problematical especially in the case of pigmented inks, ie. inks comprising dispersed colorant particles, and finally they should be environmentally compatible, ie. be substantially based on water as liquid phase and include organic solvents only in small amounts, if at all. In addition, the prints obtained have to meet coloristic requirements, ie. show brilliance and depth, and have good fastness properties, eg. rub fastness, lightfastness and water fastness or washfastness in the case of textile printing.
Existing ink-jet inks include not only pigment, dispersant and optionally further assistants but also, at the same time, a binder component, for example a UV-curable binder (EP-A-658 607, JP-A-48922/1996) or a thermally curable binder (EP-A-753 552, EP-A-412 548).
In these inks, the individual constituents have to be in perfect harmony to obtain storage-stable, noncoagulating inks having good flow behavior and good fastness properties, which can lead to difficulties.